The man who propagated first Christianity outside Palestine was Paul

From: "The Bible came from Arabia" of Kamal Salibi 

Today, many scholars take the view that the Gospel writers acquitted Pilate of responsibility for the death of Jesus in order to make Christianity more palatable to the Roman Gentiles. But in fact the Gospels largely represent the point of view of the Hebraic party among the apostles. 

The man who first began to encourage the propagation of Christianity among the Gentiles, including the Romans, was Paul, who had nothing to do with the writing of the Gospels. Furthermore, the Jewish historian Josephus, writing three or four decades after the death of Jesus, endorsed what is written in the Gospels and by Paul about the Jewish responsibility for his execution. He wrote in the Antiquities (18:3:3): 'Pilate, at the suggestion of the principal men amongst us . . . condemned him to the cross.' So much, or perhaps slightly more, can be deduced about the historical Jesus from the Gospels, with the help of the little other material available; and Paul recognized this same historical Jesus as being his Christ. As already noted, Paul had probably never met this Jesus in life. What remains highly significant, however, is that when Paul decided to become a follower and apostle of Jesus, he did not go to find information about him in Jerusalem, among his original disciples who still lived in the city, as one would have expected. Oddly enough, and by his own sworn testimony ('What I write is true! God knows I am not lying!', Galatians 1:20), he went directly to Arabia instead. The first-hand information he needed about Jesus  either as a man, or as the promised Jewish Messiah  was to be found in Arabia rather than in Jerusalem. This means that the historical Jesus had some connection with Arabia. He was either a man who came from there, or the representative of an Israelite religious or political movement whose original centre was Arabian. Perhaps he was both. Paul's visit to Arabia is a historical fact. Yet the book of Acts, representing the predelictions of the Jerusalem apostles whom Paul never consulted about Jesus, made a point of ignoring it. This suggests that there was a great secret involved.

Judaism, Christianity and Islam

Monotheistic religions of the Middle East and the pursuit of power by any means
Danilo Anton

These thoughts only seek to show some aspects of organized monotheistic religions that virtually  since their inception were used as tools to obtain and retain power and to gain control of territories, resources, societies and minds.
From the point of view of the number of believers and their influence on the political and social geography of these nations the three main religions, Judaism, Christianity and Islam are the most important in the world history. All three of them originated in the Middle East.

Judaism emerged as a set of traditions, originally transmitted orally, that narrate the legendary history of a people influenced by the intervention of one God, Jehovah (in Hebrew יהוה transliterated YHWH). This story is contained in the Torah, a sacred book that contains the foundational narrative of the Jewish people: their trials and tribulations, and its covenant with God. It describes a way of life to follow embodied in a set of moral and religious obligations and civil laws. While the first prophet (Abraham) has lived in the twentieth century BCE and the second prophet, Moses, who received the divine commandments in the twelfth century BC, Most biblical scholars believe that the Torah was actually written between the sixth and fourth centuries BCE, although some components may have been recorded in earlier times.
The second monotheistic religion that acquired historic importance was Christianity, which was derived from Judaism. It is based on the teachings of a prophet, Jesus, whose life is chronicled in a holy book usually called New Testament, which consists of four officially approved (or canonical) Gospels (Gospels of Matthew, Mark, Luke and John). Christianity also includes the ancient sacred books of Judaism, generically called Old Testament. The actual existence of Jesus was only confirmed by the gospels, not only official ones, but also several others that have been preserved or its fragments are known, but were not recognized by the ecclesiastical authorities. According to the biblic historians, at the beginning, the gospels were transmitted orally and only were written between 65 and 100 DEC or more than 30 years after the date on which Jesus was (probably) crucified.
Like Judaism, Christianity bases its religious system in the existence of one God and on the confirmation of the arrival of the Messiah announced by the prophets of the Old Testament, and whose death would redeem mankind from their sins. The books include also the  moral teachings transmitted by Jesus during his life.

Islam, who is also a monotheistic religion, developed in Arabia where a prophet (Muhammad), considered by his followers as sent by God (Allah), preached a faith based on the ancient jewish and christian sacred books. Muhammad added a new final divine message, the Koran, which contains the fundamental premises of the new religion.

A basic belief of the religion was that "There is no God but Allah and Muhammad is his prophet". The Quran also defines the obligations of Muslims (followers of Islam) including Islam five pillars, profession of faith, daily prayers, zakat (alms), fasting in the month of Ramadan and pilgrimage to Mecca at least once in life, and various moral teachings, many of which were included in the other holy books (Old and New Testament). They included also the life stories of the previous prophets Abraham, Moses and Jesus. Like the Torah and the Christian Bible, the Quran was memorized by Muhammad's followers and was only written or compiled several years later. Ultimately the three monotheistic religions began as oral traditions and only some years, decades or centuries later were recorded in writing.

The faithful of these three religions are numerous. There are about 2,000 million christians, 1,500 million muslims and 15 million jews. For that reason, largely, thoughts and actions of many societies that embrace these faiths are directly or indirectly influenced by the moral, social or political mandates (fulfilled or not) of these religions.

We must consider that ALL these religions originated in the Middle East (Palestine, Israel, Arabia) and since its inception the have disputed for the control of the territories and peoples of that region. The history of the Middle East is largely the confrontation of organized groups on behalf of these religions who fought successive wars for the control of lands, resources and societies.

These religions were the reason or the excuse for wars, bloody clashes, killings, rapes, looting, torture, racial or religious intolerance, enslavement or ethnic cleansing that began more than twenty centuries ago and still continue today. Not only they have these religions have violently confronted among them but their different organized divisions or sets also have bloodily fought to obtain or preserve power. These concepts apply to these organized religions, their churches, and mainly to those leaders who base their power in religion.
In that sense we can consider that monotheistic organized religions organized, almost from the beginning were used as unscrupulous tools to obtain and retain power, and to better manage resources, territories, societies and minds.
And still they are.